Night lights are as old as human civilization, the first night light being a burning torch of combustible material. With the invention of electrical power and with the further invention of light bulbs, an electrical light could be turned on at night when a night light was needed. Batteries also provided a handy, portable source of light at night, when a flashlight could be turned on at the flick of a switch.
With the invention of electrical light sensors, automatic night lights of all sorts were invented. These light sensors were used to sense the amount of ambient light in their immediate environment. When there existed considerable ambient light in the environment as for example during daytime, the sensor and associated electrical circuit would keep electrical current from flowing to an electrical bulb, and the night light would be turned off. When the ambient light fell below a certain level, as in the nighttime, the sensor and associated electrical circuit would now send electrical current to an electrical bulb and the night light would be turned on. The invention of automatic night lights were a common sense invention in that a night light was provided only when needed at dark and turned off when not needed during the daytime, so needless use of electrical power and unnecessary wear and tear on the light bulb was prevented.
There is much prior art in the existing literature and in commerce in the way of night lights. For example, one of the most utilized light sensors is the cadmium sulfide photosensor, which has a high resistance in low light and a low resistance in high light. One of the devices on sale in the commercial marketplace is a dusk-to-dawn 120V AC electrical outlet extension plug controlled by a cadmium sulfide photosensor, such that in the daytime, the extension does not allow 120V AC to flow through the extension plug, but at nighttime, the extension does allow the electrical current to flow through it. Thus, this photosensitive extension turns any lamp that is plugged into it into an automatic night light.
Another piece of relevant prior art on sale commercially is a plug-in night light that has a built-in cadmium sulfide photosensor and built-in incandescent bulb and socket, and which plugs into a standard 120V AC electrical outlet. The photosensor allows the light bulb to turn on at night but turns the light bulb off in normal daylight.
A third piece of relevant prior art commercially on sale is a plug in night light that has a built-in cadmium sulfide photosensor and built-in light emitting diodes (LEDs), and which plugs into a standard 120V AC electrical outlet. The photocell allows the LEDs to turn on at night but turns the LEDs off in normal daylight. LEDs have certain advantages over incandescent light bulbs in that LEDs use less power than incandescent light bulbs to produce an equal amount of light. That is, LEDs are more efficient at producing light than incandescent light bulbs. Also, LEDs are much smaller than light bulbs. Finally, LEDs do not have filaments that wear out frequently like those in light bulbs, so that LEDs last much longer than light bulbs. However, a disadvantage of this prior art device is that standard LEDs are utilized, which such LEDs are rather bulky, being shaped as cylinders with rounded tops with a diameter of 0.5 cm and height of 1.0 cm.
The problem with these prior art night lights is that they are separate units which must be plugged into standard 120V AC electrical outlets to work. In this situation, they take out of operation one of the available electrical outlets from being otherwise usefully available. Also, aside from being of some use at the location of electrical outlet end plates, such plug in night lights are not operational at the locations of either blank electrical end plates or electrical switch end plates. There is a commercially available switch for a switch type end plate in which the switch has an LED embedded in the toggle part of the switch and which aids a person seeing the switch at night so that it can be turned on. However, the LED always stays on and does not turn off at night. Thus, this prior art is not actually an automatic night light, but rather a small light which remains permanently on. Another problem with this prior art is that the LEDs embedded in lit up switch toggles are not very bright, and they provide only enough light for a person to barely make out the location of the toggle. The light from the toggle is not sufficient to light up the area around the light switch such as the floor so as to provide light enough to walk in that area at night.
Another piece of relevant prior art is U.S. Pat. No. 4,546,419 for a wall receptacle night light by Kelli Johnson. Johnson discloses a night light module that does fit into a standard size electrical box and which taps the 120V AC coming into the said electrical box for its power. However, the module utilizes an incandescent light bulb, the filament of which tends to wear out in contrast to LEDs which have no filament to wear out, and which consequently, last much longer. The incandescent light bulb in Johnson's invention draws much more electric current than the LED in the present invention. Also, Johnson's module allows room for only a single electrical outlet when it is placed inside a standard single type electrical box. In contrast, the invention described in this specification allows the use of two electrical outlets when connected to a standard single type electrical box. Another disadvantage of Johnson's invention is that it does not work with a standard type single electrical switch type end plate in conjunction with a standard single type electrical switch box. It will work with a standard double type electrical box which incorporates a switch, but such an electrical box is considerably larger than a single electrical box and corresponding end plate. The present invention described herein does fit into a single type electrical box and corresponding single switch end plate. Another disadvantage of Johnson's invention is that the whole module of her invention is one complete unit in which the end plate is not separable from the power supply/trigger circuit of the device. In the present invention described here, the end plate and the power supply/trigger circuit can be easily unplugged from each other for greater convenience and safety when dealing with the potentially dangerous 120V AC source coming into the electrical box. Thus, in this present invention, it is easy to take off the night light end plate and restore the standard plain end plate if desired, leaving the power supply/trigger circuit with its potentially dangerous 120V AC contacts out of the way, in the back of the electrical box.
Therefore, it is one objective of the present invention to be described herein to provide electrical end plates of either the blank, outlet, or switch types, that possess a built in night light. It is another objective of the present invention that the end plates with a built in night light are such that they can be easily installed to replace standard end plates that do not possess a night light, and that such night light end plates be compatible with standard 120V AC electrical boxes.
Such objectives are achieved with the present invention by virtue of a small compact electronic photosensor/photoemitter circuit that is incorporated into an otherwise standard end plate along with a small compact power supply/trigger circuit that fits into the back of a standard electrical box and that taps into the 120V AC feeding into the said electrical box.